Searching PubMed for studies on bacteremia, bloodstream infection, septicemia, or whatever the best term is: A note of caution

BACKGROUND: There is inconsistency in the terminology used to describe bacteremia. To demonstrate the impact on information retrieval, we compared the yield of articles from PubMed MEDLINE using the terms "bacteremia," "bloodstream infection," and "septicemia." METHODS: We searched for articles published between 1966 and 2009, and depicted the relationships among queries graphically. To examine the content of the retrieved articles, we extracted all Medical Subject Headings (MeSH) terms and compared topic similarity using a cosine measure. RESULTS: The recovered articles differed greatly by term, and only 53 articles were captured by all terms. Of the articles retrieved by the "bacteremia" query, 21,438 (84.1%) were not captured when searching for "bloodstream infection" or "septicemia." Likewise, only 2,243 of the 11,796 articles recovered by free-text query for "bloodstream infection" were retrieved by the "bacteremia" query (19%). Entering "bloodstream infection" as a phrase, 46.1% of the records overlapped with the "bacteremia" query. Similarity measures ranged from 0.52 to 0.78 and were lowest for "bloodstream infection" as a phrase compared with "septicemia." CONCLUSION: Inconsistent terminology has a major impact on the yield of queries. Agreement on terminology should be sought and promoted by scientific journals. An immediate solution is to add "bloodstream infection" as entry term for bacteremia in the MeSH vocabulary.